Bouncing Back and Back and Back and Back

Natural structures have long inspired human innovations. The bee honeycomb structure, for example, has been applied to products as varied as car bumpers and athletic helmets to absorb impact.

The only drawback to the honeycomb has been its inability to maintain its unique structure after just one hit. The material buckles and doesn't bounce back.

The Cockrell School of Engineering Facts & Figures

  • 7,700 students enrolled in nine undergraduate and 13 graduate degree programs
  • 280 professorial faculty
  • Senior faculty constitute the fourth-highest membership in the National Academy of Engineering, the nation's highest honor for engineers
  • Undergraduates enrolled in the Cockrell School in 2014-15 received more than 1,300 scholarships, totaling over $6 million. The Cockrell School awarded $4 million to more than 450 graduate students in fellowship support during 2014-15.

Average Annual Starting Salaries, Engineering 2013-14

(bachelor's degree recipients, in industry)

  • Average $73,039
  • Aerospace $69,612
  • Architectural $58,476
  • Biomedical $66,732
  • Chemical $76,608
  • Civil $58,260
  • Electrical $72,348
  • Mechanical $71,484
  • Petroleum $90,012
To solve this problem, researchers in the Cockrell School of Engineering developed a groundbreaking honeycomb-inspired energy-absorbing structure to better withstand blunt and ballistic impact. It's called a negative stiffness (NS) honeycomb, and it could have huge implications for the design and production of future vehicles, military gear and athletic equipment.

In short, NS honeycombs bounce back when other honeycombs do not.

"Whether you’re serving our country in uniform, playing in a big game, or just driving or biking to work, the potential for multiple collisions or impacts over time — however big or small — is a reality," says Carolyn Conner Seepersad, professor of mechanical engineering, who led the work along with UT Austin research scientist Michael Haberman.

"We believe that this technology, when constructed in future helmets and bumpers, could reduce or even prevent many of the blunt-force injuries we see today." —Carolyn Conner Seepersad

The UT Austin team’s research on the innovative structure was published in Integrated Materials and Manufacturing Innovation.

The researchers devised a cell geometry capable of elastic buckling, giving NS honeycomb structures the resilience to recover their energy-absorbing shape and properties after impact. The cell dimensions can be customized to withstand different amounts of force, translating to a variety of versatile applications.

In 2014, the research team received a Small Business Innovation Research Grant from the U.S. Department of Defense. That funding and additional collaboration with the Maritime Applied Physics Corporation, an engineering company that frequently partners with the U.S. military, helped support the advancement of NS honeycomb technology.

The next phase of assessment will include ballistic testing. The researchers are also building a lab prototype of an enhanced combat helmet with NS honeycomb cells integrated that will be completed this fall.

Honeycomb-inspired design. Impact-absorbing tech. Protecting our soldiers and athletes. That’s how we change the world!

Negative Stiffness Honeycomb